-LRB- CNN -RRB- -- George H.W. Bush turns 90 today -LRB- June 12 -RRB- , only the fourth American president to reach that age . He 's the last of the World War II presidents , the last American leader to preside over the Cold War , the last of a generation of elected leaders who saw themselves as old-fashioned public servants rather than cutthroat campaigners .

Today , there are college graduates who were n't even born when he left office . So the question is , what can 20-somethings learn from an old man like Bush ?

It starts with what Bush said to a group of young people in one of the last speeches he gave as President : `` What all of us seek in our life is meaning and adventure . It 's through service that all of us can find both . ''

He certainly has had 90 years of `` meaning and adventure '' â $ '' flying as one of the youngest Navy pilots in World War II ; serving in Congress during the 1960s ; as US liaison to China in the days of Mao ; as chair of the Republican Party during Watergate ; as head of the CIA after the Church Commission ; as Ambassador to the United Nations during the Cold War ; as Vice President during the Reagan Revolution ; as President during the collapse of the Soviet Union .

And as a post-presidential humanitarian , he has raised millions for cancer research and disaster relief alongside the man who was his most bitter political rival .

Bush had a front-row seat to most of the major events of the second half of the 20th century , and he did it by dedicating his life to service to others .

`` Public service is a noble calling , '' something he 's said so often that it 's engraved on a bust at his Bush School of Government and Public Service at Texas A&M University . -LRB- The students rub its brass nose for good luck ; he once quipped , `` Thank God it was only a bust ! '' -RRB-

I asked about Bush 's formula for meaning and adventure when I interviewed 41 extraordinary people for our new documentary about our 41st president , `` 41ON41 . '' Many of the 41 spoke of Bush 's lifelong commitment to public service , whether in uniform , in appointed positions , through elected office or in community service .

`` This man has affected this country and served this country in so many ways , '' said sports commentator Jim Nantz , `` and he 's done it every step of the way with a kind heart , with good intentions , with real concern that he 's doing the right thing to help people . ''

`` I do believe , if there were more people like him , the world would be a better place , '' President Bill Clinton told me . `` If your primary motivation is to serve , then , in an imperfect world , you 're likely to make the right rather than the wrong compromises .

`` His primary motivation was to serve . You do n't get to pick the time you serve , and you ca n't control the circumstances in which you govern . There 's always some good and some bad in it . But he made the most of a hand that was not the easiest hand to play . And he did it because , at heart , he 's a servant . ''

Pierce Bush is G.H.W. 's grandson , and the two have talked about the day his grandfather decided to make the first step in a lifetime of service .

`` He remembers sitting in an Andover -LSB- High School -RSB- auditorium right after Pearl Harbor was attacked , '' Pierce said . `` There was this spirit that he wanted to be a part of . He wanted to go and defend America , he wanted to be a part of something bigger than himself . ''

Pierce sees the parallels with his generation -- in the same longing millennials have to be a part of something larger than oneself . His Twitter homepage quotes his grandfather : `` Any definition of a successful life must include service to others . ''

Pierce works for Big Brothers Big Sisters in Houston and would tell you that his life is full of both meaning and adventure .

Condoleezza Rice is concerned that young people have only seen the worst of elected officials in a gridlocked Washington that seems to feed on character assassination . She knows how hard it is to decide to go into public service in such a poisonous environment .

`` I would say to young people : Never forget that democracy depends on its citizens to care about it , to promote it , to work for it , '' Rice said . `` Democracies do n't survive if citizens simply leave it to others to do the hard work of governing , and so if you get a chance to be in public service , do it . The greatest thing that you can do in your life is to serve your country . You could have no better role model than George H. W. Bush . ''

Bush 's life is full of lessons for young people . I hope you 'll tune in to CNN on Father 's Day at 9 p.m. ET to hear more about this remarkable American life . You 'll be surprised how much you 'll learn .

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Mary Kate Cary : George H.W. Bush , turning 90 , is recognized for his service

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She says he sought to have a life of `` meaning and adventure '' and succeeded

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Cary : 41st President has much to teach millennials looking to make a difference in life

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She a produced film , airing on CNN , with interviews of 41 who know Bush best